import csv
import smtplib
from email.mime.text import MIMEText
from random import shuffle

# 1. Load participants from CSV, now including id and last_match_id
def load_participants(filename):
    participants = []
    with open(filename, 'r') as file:
        reader = csv.DictReader(file)
        for row in reader:
            participants.append({
                'id': int(row['id']),
                'name': row['name'],
                'household': row['household'],
                'email': row['email'],
                'last_match_id': int(row['last_match_id']) if row['last_match_id'] else None
            })
    return participants

# 2. Backtracking algorithm to find valid matches
def find_matches(givers, receivers, matches, used_receivers):
    if len(matches) == len(givers):
        return True  # Found a complete set of matches

    giver = givers[len(matches)]  # Process the next giver

    for receiver in receivers:
        # Check constraints: different person, different household, no last-year match, no reciprocal match
        if receiver['id'] not in used_receivers and \
                giver['id'] != receiver['id'] and \
                giver['household'] != receiver['household'] and \
                giver['last_match_id'] != receiver['id'] and \
                matches.get(receiver['id']) != giver['id']:

            # Assign receiver to giver
            matches[giver['id']] = receiver
            used_receivers.add(receiver['id'])

            # Recurse with the next giver
            if find_matches(givers, receivers, matches, used_receivers):
                return True  # Solution found

            # Backtrack: remove the match and try another receiver
            del matches[giver['id']]
            used_receivers.remove(receiver['id'])

    return False  # No valid match found, backtrack

# 3. Wrapper function to initialize and run the backtracking
def generate_complete_matches(participants):
    givers = participants.copy()
    receivers = participants.copy()
    shuffle(givers)  # Shuffle for variety
    shuffle(receivers)  # Shuffle for variety

    matches = {}
    used_receivers = set()

    # Start backtracking
    if find_matches(givers, receivers, matches, used_receivers):
        return matches
    else:
        print("Could not find a complete set of matches.")
        return None

# 4. Confirm matches interactively
def confirm_matches(participants, matches):
    print("Proposed Matches:")
    for giver_id, receiver in matches.items():
        giver = next(p for p in participants if p['id'] == giver_id)
        print(f"{giver['name']} ({giver['email']}) will give a gift to {receiver['name']} ({receiver['email']})")
        response = input("Approve this match? (yes/no): ").strip().lower()
        if response != 'yes':
            print("Match not approved. Restarting the matching process...\n")
            return False  # Signal to restart if any match is disapproved
    return True

# 5. Final confirmation to save matches
def final_confirmation(participants, matches):
    print("\nFinal Match List:")
    for giver_id, receiver in matches.items():
        giver = next(p for p in participants if p['id'] == giver_id)
        print(f"{giver['name']} will give a gift to {receiver['name']}")

    # Final save prompt
    response = input("\nDo you want to save this match list? (yes to save, no to restart): ").strip().lower()
    return response == 'yes'

# 6. Update last matches in the CSV file
def update_last_match_in_file(participants, matches, filename):
    for giver_id, receiver in matches.items():
        for participant in participants:
            if participant['id'] == giver_id:
                participant['last_match_id'] = receiver['id']

    with open(filename, 'w', newline='') as file:
        fieldnames = ['id', 'name', 'household', 'email', 'last_match_id']
        writer = csv.DictWriter(file, fieldnames=fieldnames)
        writer.writeheader()
        for participant in participants:
            writer.writerow({
                'id': participant['id'],
                'name': participant['name'],
                'household': participant['household'],
                'email': participant['email'],
                'last_match_id': participant['last_match_id']
            })
    print("Matches saved to 'participants.csv'.")

# 7. Email sending function
# 7. Email sending function with improved formatting
def send_emails(matches, participants, sender_email, smtp_server, smtp_port, login, password):
    for giver_id, receiver in matches.items():
        giver = next(p for p in participants if p['id'] == giver_id)

        # Compose email
        subject = "Dein Wichtel-Match für Weihnachten 2025"
        message = (
            f"Hallo liebe/r {giver['name']},\n\n"
            f"Dein Match für das diesjährige Wichteln ist {receiver['name']}.\n\n"
            "Grüße,\n"
            "Das Wichtelsystem\n\n"
            "--Bitte beachtet, dass für ungefähr 25€ gewichtelt wird--"
        )

        # Prepare email
        msg = MIMEText(message, 'plain')
        msg['Subject'] = subject
        msg['From'] = sender_email
        msg['To'] = giver['email']

        # Send email
        try:
            with smtplib.SMTP(smtp_server, smtp_port) as server:
                server.starttls()  # Secure the connection
                server.login(login, password)
                server.sendmail(sender_email, giver['email'], msg.as_string())
            print(f"Email sent to {giver['name']} at {giver['email']}")
        except Exception as e:
            print(f"Error sending email to {giver['name']} ({giver['email']}): {e}")


# 8. Main function to run the match process
def main():
    participants = load_participants('participants.csv')
    while True:
        matches = generate_complete_matches(participants)
        if matches and confirm_matches(participants, matches):
            if final_confirmation(participants, matches):
                update_last_match_in_file(participants, matches, 'participants.csv')

                # Send emails after saving the matches
                sender_email = "weihnachtswichteln0@gmail.com"  # Update to your email
                smtp_server = "smtp.gmail.com"         # Update to your SMTP server
                smtp_port = 587                          # Typically 587 for TLS
                login = "weihnachtswichteln0@gmail.com"         # SMTP login
                password = ""              # SMTP password

                send_emails(matches, participants, sender_email, smtp_server, smtp_port, login, password)
                break
            else:
                print("\nRestarting the matching process...\n")
        else:
            print("No complete match found, restarting...\n")

if __name__ == '__main__':
    main()